Drum-shaped knife cage with replaceable knife sets

ABSTRACT

Drum-shaped knife cage assembly including a drum-shaped knife cage, a multiplicity of knife crosspieces disposed on the periphery of the drum-shaped knife cage and having respective knife support surfaces extending in axial direction of the drumshaped knife cage and disposed at an acute angle to a radial plane through the drum-shaped knife cage, a knife set including a knife holder plate and shredding knives held thereby supported on one of the knife support surfaces, and clamping means engaging the knife crosspiece for clamping the respective knife set against the respective knife support surface of the knife crosspiece, the knife holder plate being beveled at both ends thereof to form a wedge surface thereat, the wedge surface, as viewed in cross section parallel to the longitudinal axis of the knives and perpendicular to the knife support surface, defining with the knife support surface an acute angle, the clamping means including a separate clamping device at each end of a respective knife holder plate, each of the clamping devices having a wedge counter-bearing surface corresponding to the wedge surface of the knife holder plate, at least one of the clamping devices including a releasable clamping jaw.

United States Patent Maier et a1.

Sept. 9, 1975 1 DRUM-SHAPED KNIFE CAGE WITH REPLACE/ABLE KNIFE SETS [75] Inventors: Gerhard Maier; Werner Grube,

both of Brackwede; Johannes Schrage, Brackwede-Holtkamp. all of Germany [73] Assignee: B. Maier KG, Brackwede, Germany [22] Filed: Apr. 11, 1974 [21] Appl. No.: 460,186

[30] Foreign Application Priority Data Apr. 13, 1973 Germany 2318730 [52] US. Cl. 241/286; 83/3563; 83/698; 241/221; 241/2921 [51] Int. Cl. B02C 18/18 [58] Field of Search 241/191, 192, 221, 282.2, 241/286, 292.1, 300.1; 144/172, 212; 83/3563, 698, 699, 856

[56] References Cited UNITED STATES PATENTS 2.381.775 8/1945 Roddy 241/191 UX 3.1415185 7/1964 Bonner at al. 241/191 X 3355.113 11/1967 Megcr 241/191 3.827.643 8/1974 Grube ct a1 241/221 Primary Examiner-Granville Y. Custer, Jr. Assistant Examiner-Howard N. Goldberg Attorney, Agent, or FirmHerbert L. Lerner 5 7 1 ABSTRACT Drum-shaped knife cage assembly including a drumshaped knife cage, a multiplicity of knife crosspieces disposed on the periphery of the drum-shaped knife cage and having respective knife support surfaces extending in axial direction of the drum-shaped knife cage and disposed at an acute angle to a radial plane through the drum-shaped knife cage, a knife set including a knife holder plate and shredding knives held thereby supported on one of the knife support surfaces, and clamping means engaging the knife crosspiece for clamping the respective knife set against the respective knife support surface of the knife cross piece, the knife holder plate being beveled at both ends thereof to form a wedge surface thereat, the wedge surface, as viewed in cross section parallel to the longitudinal axis of the knives and perpendicular to the knife support surface, defining with the knife support surface an acute angle, the clamping means including a separate clamping device at each end of a respective knife holder plate, each of the clamping devices having a wedge counter-bearing surface corresponding to the wedge surface of the knife holder plate, at least one of the clamping devices including a releasable clamping jaw.

4 Claims, 6 Drawing Figures PATENTEU 9W5 3 904 1 39 SPEU 1 UP 3 Fig 3 Fig. 4

PATENTED SEP 9 I975 saw 3 0g 3 DRUM-SHAPED KNIFE CAGE \VITH REPLACEABLE KNIFE SETS The invention relates to a drum-shaped knife-blade cage and, more particularly, to such a knife cage having replaceable knife packets or sets formed of knife holder plates and knives or blades for a shredding device, particularly for preliminary or coarsely comminuted wood, with knife crosspieces that are disposed at the periphery of the knife cage and, respectively, have a knife support surface for the knife sets which extend in axial direction and are respectively disposed at an acute angle to the radial plane, and with clamping devices supported at the knife crosspieces for clamping the knife sets against the knife support surfaces of the knife crosspieces.

It has been known heretofore to construct such a clamping device as a bell crank or toggle lever mechanism. This form of construction is satisfactory with respect to the speed of replacement or exchange of the knife sets, but an increasing tendency of the knife cage to get clogged, especially if the chips are moist, has been found to be disadvantageous. Also, it is somewhat difficult to operate such a toggle lever mechanism manually.

It is accordingly an object of the invention to provide a knife cage of this general type, with clamping devices for the knife sets, the knife cage being of such construction that the clamping devices do not interfere with the removal of the chips. It is a further object of the invention to provide such a knife cage wherein manual operation is considerably facilitated in comparison to heretofore known devices of this type.

With the foregoing and other objects in view, there is provided in accordance with the invention a drum shaped knife cage assembly comprising a drum-shaped knife cage, a multiplicity of knife crosspieces disposed on the periphery of the drumshaped knife cage and having respective knife support surfaces extending in axial direction of the drum-shaped knife cage and disposed at an acute angle to a radial plane through the drum-shaped knife cage, a knife set comprising a knife holder plate and shredding knives held thereby sup ported on one of the knife support surfaces, and clamping means engaging the knife crosspiece for clamping the respective knife set against the respective knife support surface of the knife crosspiece, the knife holder plate being beveled at both ends thereof to form a wedge surface thereat, the wedge surface, as viewed in cross section parallel to the longitudinal axis of the knives and perpendicular to the knife support surface, defining with the said knife support surface an acute angle, the clamping means comprising a separate clamping device at each end of a respective knife holder plate, each of the clamping devices having a wedge counter-bearing surface corresponding to the wedge surface of the knife holder plate, at least one of the clamping devices comprising a releasable clamping jaw.

Due to the disposition of the clamping devices at the ends of the knife sets, the knife holder plates are free of any interfering structures along the entire length thereof (except their ends). Free runoff of the chips is thereby ensured. The knife support surfaces of the individual cage crosspieces are furthermore readily acces sible, after the knife sets are removed, and are therefore relatively easy to clean.

As noted hereinbefore, in accordance with the invention, it is advantageous if only one of the two wedge counter-bearing surfaces, which are located at the two ends of a knife holder plate, is constructed as a releasable clamping jaw. The other wedge counter-bearing surface is advantageously formed by a rigid jaw fixed to the knife holder plate. The latter is generally fastened at one end of the respective knife cage cross piece. This has the advantage that the knife set need be placed only on the knife support surface of the knife cage cross piece, and the knife holder plate pushed with the wedge surface thereof underneath the matching or opposing wedge surface of the fixed jaw. Then, only the releasable clamping jaw with its mating wedge surface need to be clamped against the other wedge surface of the knife holder plate. Clamping is generally achieved by screwing the clampingjaw to the knife cage crosspiece. To fasten the knife set itself, only a single manipulation is basically required, namely to tighten the releasable clamping jaw bolts.

Of course, other fastening means for the clamping jaws may also be used. Particularly advantageous might be a capstan-head screw.

Appropriate measures are required to take up or absorb the cutting pressure of the knife set acting in the knife support plane. In the heretofore known clamping devices, keys are provided, for example, for this purpose. The keys are disposed in longitudinal slots of the knife holder plate and abut the clamping device, thereby absorbing the cutting pressure. Such a heretofore known construction cannot, however, be used with the invention of the instant application since the clamping devices of the invention of this application are located only at the ends of the individual knife holder plate.

In accordance with a further feature of the invention the wedge surfaces as well as the corresponding matching or opposing wedge counterbearing surfaces define an acute angle with the respective knife support surface, as viewed in a cross section perpendicular to the axis of the knife cage, so that, in the clamped condition, the wedge surface and wedge counter-bearing surface introduce a force component counteracting the cutting pressure. The wedge surfaces therefore introduce a force component normal to the knife support surface of the knife cage crosspiece, as well as a force component counteracting the cutting pressure. Thereby, any construction such as aforementioned keys and associ ated keyways, for example, can be eliminated. The de vice is thereby greatly simplified.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a drum-shaped knife cage with replaceable knife sets, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with accompanying drawings, in which:

FIG. 1 is a side elevational view of a segment of a knife or blade cage constructed in accordance with the invention;

FIG. 2, is a fragmentary diagrammatic plan view as seen from the upper right-hand corner of FIG. 1;

FIGS. 3 and 4 are views similar to those of FIGS. 1 and 2, respectively, of a modified form of the invention wherein a key for absorbing the cutting pressure is additionally provided at the crosspiece l of the knife cage assembly, and;

FIGS. 5 and 6 are perspective views of a segment of the knife cage assembly with a knife set and a knife holder plate corresponding to FIGS. I and 3, respectively.

Referring now to the drawing and first, particularly, to FIGS. 1 and 2 thereof, there is shown one of a multiplicity of knife cage crosspieces 1, that are uniformly distributed over the periphery of a knife cage and extend in a direction parallel to the non-illustrated axis of the knife cage. The cross section of these knife cage crosspieces, as seen in FIG. 1, is substantially triangular. They carry on one of their outer surfaces socalled knife sets, respectively including knives 2 and a knife holder plate 3. On the other outer side of each of the knife cage crosspieces 1, a stock shave or knife 4 is secured. The inner side of the substantially triangular crosspiece l which faces radially inwardly to the knife cage, is covered by a wear-resistant pressure plate 5.

A clamping jaw 6 is releasably attached to the knife cage crosspiece l at one end thereof by a screw 7. This clamping jaw 6 together with an opposing wedge surface 8 abut a corresponding wedge surface 9 of the knife holder plate 3 (note FIG. 2 particularly). The wedge surface 9 of the knife holder plate 3 is inclined, as shown in FIG. 1, in such a manner that it both provides a normal force for pressing the knife holder plate 3 perpendicularly against the knives 2, as well as has the capability in that position of withstanding the cutting pressure which is exerted on the knives 2 (note also FIG. 5).

The clamping jaw 6, as is apparent from FIG. 2, has a shape similar to that of a U-shaped angle iron, which is particularly advantageous. It is conceivable, however, for the clamping jaw 6 to be somewhat L-shaped.

With respect fo FIG. 2, it is noted that this figure represents only the left-hand side of the assembly and that the non-illustrated right-hand side thereof may be a duplicate mirror-image of FIG. 2 which includes a second releasable clamping jaw 6. Alternatively, as can be seen in FIG. 5, for example, at the bottom of that figure, a non-releasable or fixed clamping jaw 6' may be provided.

The knife cage 10 according to the modified embodiment illustrated in FIGS. 3 and 4 includes a special device, namely a key 20, which takes up or absorbs the cutting pressure that is exerted on the knives 2. The key 20 is threadedly or otherwise secured to the knife cage crosspiece l as represented diagrammatically by the dot-dash line. The key 20 engages in a keyway 21 suitably formed in the knife holder plate 3 (note also FIG. 6).

Due to the disposition of the key and the keyway as shown in FIGS. 3 and 6, the Wedge surfaces and opposing or matching wedge surfaces need be inclined with respect to each other only in a single plane, since they do not have to take up or absorb the cutting pressure. These pairs of surfaces are therefore disposed, as may also be seen in FIG. 6, in such a way that the longitudinal axes of the surfaces extend parallel to each other.

It is immaterial to the invention of this application, whether the knife cage is cylindrical or conical, or whether it is stationary or rotatably supported.

We claim:

1. Drum-shaped knife cage assembly comprising a drum-shaped knife cage, a multiplicity of knife crosspieces disposed on the periphery of said drum-shaped knife cage having respective knife support surfaces extending in axial direction of said drum-shaped knife cage and disposed at an acute angle to a radial plane through said drum-shaped knife cage, a knife set comprising a knife holder plate and shredding knives held thereby supported on one of said knife support surfaces, and clamping means engaging said knife crosspiece for clamping the respective knife set against the respective knife support surface of said knife cross piece; said knife holder plate being beveled at both ends thereof to form a wedge surface thereat, said wedge surface, as viewed in cross section parallel to the longitudinal axis of the knives and perpendicular to the knife support surface, defining means with said knife support surface an acute angle, said clamping means comprising a separate clamping device at each end of a respective knife holder plate, each of said clamping devices having a wedge counterbearing surface corresponding to said wedge surface of said knife holder plate, at least one of said clamping devices comprising a releasable clamping jaw.

2. Knife cage assembly according to claim 1 wherein the other of said clamping devices is rigid with the respective knife cage crosspiece.

3. Knife cage assembly according to claim 2 wherein said jaw forms an integral part of said crosspiece.

4. Knife cage assembly according to claim 1 wherein said wedge counter-bearing surface, as well as said wedge surface of said knife holder plate define an acute angle with the respective knife support surface, as viewed in a cross section perpendicular to the axis of said knife cage so that, in clamped condition, said wedge surface and said wedge counter-bearing surface introduce a force component counteracting the cutting pressure. 

1. Drum-shaped knife cage assembly comprising a drum-shaped knife cage, a multiplicity of knife crosspieces disposed on the periphery of said drum-shaped knife cage having respective knife support surfaces extending in axial direction of said drum-shaped knife cage and disposed at an acute angle to a radial plane through said drum-shaped knife cage, a knife set comprising a knife holder plate and shredding knives held thereby supported on one of said knife support surfaces, and clamping means engaging said knife crosspiece for clamping the respective knife set against the respective knife support surface of said knife crosspiece; said knife holder plate being beveled at both ends thereof to form a wedge surface thereat, said wedge surface, as viewed in cross section parallel to the longitudinal axis of the knives and perpendicular to the knife support surface, defining means with said knife support surface an acute angle, said clamping means comprising a separate clamping device at each end of a respective knife holder plate, each of said clamping devices having a wedge counterbearing surface corresponding to said wedge surface of said knife holder plate, at least one of said clamping devices comprising a releasable clamping jaw.
 2. Knife cage assembly according to claim 1 wherein the other of said clamping devices is rigid with the respective knife cage crosspiece.
 3. Knife cage assembly according to claim 2 wherein said jaw forms an integral part of said crosspiece.
 4. Knife cage assembly according to claim 1 wherein said wedge counter-bearing surface, as well as said wedge surface of said knife holder plate define an acute angle with the respective knife support surface, as viewed in a cross section perpendicular to the axis of said knife cage so that, in clamped condition, said wedge surface and said wedge counter-bearing surface introduce a force component counteracting the cutting pressure. 